漫话Redis源码之二十二

这里主要是校验，确定配置文件是否被设置：

/* This function is for checking whether sentinel config file has been set,
 * also checking whether we have write permissions. */
void sentinelCheckConfigFile(void) {
    if (server.configfile == NULL) {
        serverLog(LL_WARNING,
            "Sentinel needs config file on disk to save state. Exiting...");
        exit(1);
    } else if (access(server.configfile,W_OK) == -1) {
        serverLog(LL_WARNING,
            "Sentinel config file %s is not writable: %s. Exiting...",
            server.configfile,strerror(errno));
        exit(1);
    }
}
 
/* This function gets called when the server is in Sentinel mode, started,
 * loaded the configuration, and is ready for normal operations. */
void sentinelIsRunning(void) {
    int j;
 
    /* If this Sentinel has yet no ID set in the configuration file, we
     * pick a random one and persist the config on disk. From now on this
     * will be this Sentinel ID across restarts. */
    for (j = 0; j < CONFIG_RUN_ID_SIZE; j++)
        if (sentinel.myid[j] != 0) break;
 
    if (j == CONFIG_RUN_ID_SIZE) {
        /* Pick ID and persist the config. */
        getRandomHexChars(sentinel.myid,CONFIG_RUN_ID_SIZE);
        sentinelFlushConfig();
    }
 
    /* Log its ID to make debugging of issues simpler. */
    serverLog(LL_WARNING,"Sentinel ID is %s", sentinel.myid);
 
    /* We want to generate a +monitor event for every configured master
     * at startup. */
    sentinelGenerateInitialMonitorEvents();
}
 
/* ============================== sentinelAddr ============================== */
 
/* Create a sentinelAddr object and return it on success.
 * On error NULL is returned and errno is set to:
 *  ENOENT: Can't resolve the hostname.
 *  EINVAL: Invalid port number.
 */
sentinelAddr *createSentinelAddr(char *hostname, int port) {
    char ip[NET_IP_STR_LEN];
    sentinelAddr *sa;
 
    if (port < 0 || port > 65535) {
        errno = EINVAL;
        return NULL;
    }
    if (anetResolve(NULL,hostname,ip,sizeof(ip),
                    sentinel.resolve_hostnames ? ANET_NONE : ANET_IP_ONLY) == ANET_ERR) {
        errno = ENOENT;
        return NULL;
    }
    sa = zmalloc(sizeof(*sa));
    sa->hostname = sdsnew(hostname);
    sa->ip = sdsnew(ip);
    sa->port = port;
    return sa;
}
 
/* Return a duplicate of the source address. */
sentinelAddr *dupSentinelAddr(sentinelAddr *src) {
    sentinelAddr *sa;
 
    sa = zmalloc(sizeof(*sa));
    sa->hostname = sdsnew(src->hostname);
    sa->ip = sdsnew(src->ip);
    sa->port = src->port;
    return sa;
}
 
/* Free a Sentinel address. Can't fail. */
void releaseSentinelAddr(sentinelAddr *sa) {
    sdsfree(sa->hostname);
    sdsfree(sa->ip);
    zfree(sa);
}
 
/* Return non-zero if two addresses are equal. */
int sentinelAddrIsEqual(sentinelAddr *a, sentinelAddr *b) {
    return a->port == b->port && !strcasecmp(a->ip,b->ip);
}
 
/* Return non-zero if a hostname matches an address. */
int sentinelAddrEqualsHostname(sentinelAddr *a, char *hostname) {
    char ip[NET_IP_STR_LEN];
 
    /* We always resolve the hostname and compare it to the address */
    if (anetResolve(NULL, hostname, ip, sizeof(ip),
                    sentinel.resolve_hostnames ? ANET_NONE : ANET_IP_ONLY) == ANET_ERR)
        return 0;
    return !strcasecmp(a->ip, ip);
}
 
const char *announceSentinelAddr(const sentinelAddr *a) {
    return sentinel.announce_hostnames ? a->hostname : a->ip;
}
 
/* Return an allocated sds with hostname/address:port. IPv6
 * addresses are bracketed the same way anetFormatAddr() does.
 */
sds announceSentinelAddrAndPort(const sentinelAddr *a) {
    const char *addr = announceSentinelAddr(a);
    if (strchr(addr, ':') != NULL)
        return sdscatprintf(sdsempty(), "[%s]:%d", addr, a->port);
    else
        return sdscatprintf(sdsempty(), "%s:%d", addr, a->port);
}